Preheat oven to 375 degrees. Line a baking sheet with parchment paper.
Pulse the quick oats in a food processor until almost fine. In a mixing bowl, stir together the ground oats, flour, brown sugar, baking powder, and salt until combined. Using a pastry blender, cut in the cold butter until the mixture resembles coarse crumbs. In a smaller bowl, whisk together the egg, cream, and maple syrup until smooth. Fold the cream mixture into the flour mixture until the dough is moistened and it begins to come together. More cream can be added if needed until it just begins to hold together (you do not want the dough to be sticky, but a little crumbly, holding together when pinched between two fingers. Be careful not to knead over overwork the dough, as this will result in dense scones). Turn the dough out onto a lightly floured work surface. Pat the dough out into a circle, about 1 inch thick. Using a knife or bench scraper, cut the circle into 8 triangles. Carefully transfer the scones onto the parchment lined baking sheet. Bake for 18 minutes, or until set and golden on the bottom.
To prepare the glaze: whisk together the powdered sugar, heavy cream, maple syrup, and maple extract until smooth. More cream can be added as needed to thin. The glaze should be thick, but able to be drizzled. Drizzle the scones with glaze while the scones are still warm. The glaze will set as the scones cool.